That might be the case but the real issue is that he didn't account for the fact that the riches nations in the world are backing Ukraine and they are willing to give the country a S-load of weapons and money to fight. They are also willing to do all they can to stop Russia short of direct combat. I don't think anyone saw how difficult the fight would be for Russia and its arm forces. It seems that Ukraine is only getting stronger while Russia is getting weaker.
When a woman in her early 40s driving a hatchback can destroy a tank from a safe-ish distance, using a weapon that has an interface that any gamer could figure out, yeah I'd say things have moved on from WWII: